Biometric authentication performs personal identification (or identify verification) based on biometric information such as fingerprint, iris, retina, vein, or the like, for example. The biometric authentication includes a one-to-one (or 1:1) authentication that performs the personal identification using a user identifier (hereinafter also referred to as a “user ID”) and biometric data, and a one-to-many (or 1:N, where N is a natural number greater than or equal to two) authentication that performs the personal identification using only the biometric data and without the use of the user ID. In the 1:N authentication, the biometric data that is input by optically reading the user's fingerprint, for example, is matched (or collated) with a large number of biometric data registered in a database. Hence, although the 1:N authentication requires a longer processing time than the 1:1 authentication, the 1:N authentication does not require the user ID to be input.
In a large-scale biometric authentication apparatus applied with the 1:N authentication and having one million to ten million users, for example, the authentication processing time is long because the large number of registered biometric data. Hence, the processing performance of the biometric authentication apparatus may be improved by performing the 1:N authentication by parallel processing using a plurality of processing apparatuses such as authentication servers. In this case, the database in which the biometric data are registered may be distributively arranged in the plurality of processing apparatuses, that is, distributively stored and managed by the plurality of processing apparatuses.
On the other hand, the registered biometric data include biometric data having various qualities. For this reason, in a case in which low-quality biometric data are biasedly arranged in specific processing apparatuses, there is a possibility that the processing performance of only the specific processing apparatuses will deteriorate. When the processing performance of only the specific processing apparatuses deteriorates, the authentication processing time may greatly differ amongst the plurality of processing apparatuses, making it difficult to take advantage of the parallel processing using the plurality of processing apparatuses, and the processing performance of the biometric authentication apparatus as a whole may deteriorate.
In addition, when the quality of the registered biometric data is too low, the authentication processing time may become short due to the authentication being cancelled by the processing apparatus at an early stage of the authentication, or the authentication processing time may become long abruptly when the quality of the registered biometric data becomes lower than a predetermined quality level. Accordingly, a relationship between the quality of the registered biometric data and the processing time of the authentication performed by the processing apparatus changes depending on a matching algorithm that is used to match the input biometric data with the registered biometric data, and it is difficult to reduce and smoothen the inconsistencies in the processing times of the authentication amongst the plurality of processing apparatuses by simply arranging the low-quality biometric data so as not to be biasedly arranged in the specific processing apparatuses.
Furthermore, a plurality of qualities may be defined with respect to the biometric data, and the relationship between the quality of the biometric data and the authentication processing time is complex. The qualities defined with respect to the biometric data may include an image quality determined according to contents of the biometric data, a registered data quality determined according to contents of the biometric data that is generated from biometric data that are input a plurality of times, for example, when registering the biometric data, or the like. For this reason, the processing performance of the biometric authentication apparatus as a whole cannot be improved by merely evaluating the relationship between the quality of the biometric data and the authentication processing time based on a particular index.
In the large-scale biometric authentication apparatus, amongst the registered biometric data distributively arranged in a plurality of authentication servers, the registered biometric data that actually become matching targets of the 1:N authentication are narrowed down according to the input biometric data, such that different combinations of the registered biometric data are used every time the authentication is performed. For this reason, even when the arrangement of the registered biometric data in one authentication server is modified according to past access frequencies to the registered biometric data, as proposed in Japanese Laid-Open Patent Publication No. 2009-093571, for example, such a modification of the arrangement of the registered biometric data is not effective from the viewpoint of improving the processing performance of the biometric authentication apparatus as a whole.
Accordingly, it is difficult to smoothen the processing times of the authentication amongst the plurality of processing apparatuses when performing the 1:N authentication by the parallel processing.
Examples of prior art methods and systems may be found in Japanese National Publications of International Patent Applications No. 2012-516510 and No. 2008-524750, and Japanese Laid-Open Patent Publication No. 2009-093571, for example.